Just over a year ago I was sitting at my computer in Vermont doing something – tweeting, probably, or maybe checking the baseball scores. All of a sudden an email arrived with a link to a story in the Australian Financial Review: “Revealed: Coal Under Green Attack”

I read it with the mild incomprehension one brings to the politics of any foreign country. I quailed when I saw outraged quotes from various ministers, all of whom were unknown to me, except that I remembered just enough about Australian politics to know Labor was currently in charge, and so these were the rough equivalent of the US Democrats. A man named Wayne Swan, identified as treasurer, was saying that the attack was “a disturbing development”, “deeply irresponsible” and “completely irrational and destructive”. A man named Craig Emerson, apparently the trade minister, said “they are deluding themselves”, adding that the plan, whatever it was, would “mean mass starvation”. The environment minister, Tony Burke, said that the mysterious attack was “simply designed to undermine people who are doing their jobs”. The federal resources minister, Martin Ferguson, was most concerned of all: “Reports of elaborate strategies designed to destroy Australian industries and jobs are very disturbing.” Meanwhile, the head of the Australian Coal Association, Nikki Williams, was blaming “offshore bodies” in the US for the plan, adding “we have real concerns for safety”, and the head of Rio Tinto was describing it as “economic vandalism”.

So I was worried. What on Earth were Australian green groups up to? Had police officials uncovered some campaign of sabotage? Had someone done something really stupid that would undermine climate campaigning around the globe? Was there a bomb involved? I was all the more worried because the news accounts made clear that one of my Australian colleagues, Blair Palese, was somehow mixed up in it. She’d never seemed violent to me, but it’s hard to know with people from another culture.

Climate change, after all, is basically a big maths problem, involving the quantity of carbon we want to burn and the capacity of the atmosphere to contain it.

It took me a while to wade through all the stories, one more lurid than the next (“Coal Activists’ Strategy Exposed”; “Minerals Industry’s Fury”) but for the life of me I couldn’t figure out what had caused all the fuss. The secret document obtained by the intrepid reporters appeared to be a funding proposal from Greenpeace and some other groups called ‘Stopping the Australian Coal Export Boom’ that had as its first priority “to get in front of critical projects to slow them down in the approval process”. To do this, it would work to “gradually erode public and political support for the industry” by, among other things, “lodging legal challenges”, providing “training, strategy and support for community groups” and “using a powerful visual communications strategy to tell the story of the impacts of coal and to articulate a different vision for the future”. They had other plans too: hiring “media officers” in Brisbane and Sydney, and perhaps even “organising and amplifying the voices of health professionals so that they play a central role in the debate over the future of coal”.

The reaction from government and industry didn’t make much sense. I’d always thought of Australians as a rough and ready sort of people, not prone to panic. The last time I’d visited, to contest the long-distance ski races at Falls Creek and Perisher Blue, people dismissed all sorts of actual troubles (sleet storms, fender benders) with a cheerful “She’ll be right, mate.” So why were they in such a flurry at the prospect of a “training and mentoring program for community organisers”, a “powerful narrative about the global importance of the Galilee Basin”, and a “large number of different voices combining together into a beautiful symphony”?

Then it occurred to me that perhaps this was the first time anyone had dared to say the obvious out loud: Australia’s massive deposits of hydrocarbons were a menace to the planet, and would have to be left in the ground if the world had any hope of avoiding catastrophic global warming. Maybe this was news to people in the Australian government. If so, no wonder they were shrieking.

Before we get to morality, we need to do some maths. Climate change, after all, is basically a big maths problem, involving the quantity of carbon we want to burn and the capacity of the atmosphere to contain it. All those massive Australian coal deposits are just the remains of old carbon-based life, hundreds of millions of years’ worth of it. Now we’re digging up those aeons and pouring the carbon into the air in the geological blink of an eye. The question is, how much more can we burn before we’re in trouble?

Answering that question requires that you first decide what constitutes “trouble”. The world community, including Australia, has hit on an answer: two degrees of warming. The number was first suggested by a German panel in 1995, at a meeting chaired by Angela Merkel, who was then the German minister of the environment and is now the (conservative) chancellor. It’s not a hard and fast scientific line, of course. “There [are] no hard numbers to support 2 versus 2.2 or 1.8 degrees,” said Josep Canadell, the executive director of the Global Carbon Project. If anything, it appears to be too high a target for comfort, at least for scientists. They point out that, so far, we’ve raised the temperature of the planet just 0.8 degrees, and that’s caused far more damage than any scientist expected. (Eighty per cent by volume of the summer sea ice in the Arctic is gone; the acidity of the oceans has increased by 30%.) James Hansen, a former NASA scientist and the planet’s most prominent climatologist, puts it like this: “What the paleoclimate record tells us is that the dangerous level of global warming is less than what we thought a few years ago. The target that has been talked about in international negotiations for 2 degrees of warming is actually a prescription for long-term disaster.”

Environmentalists tend to agree. Recall the 2009 Copenhagen summit on global warming, which was supposed to solve the climate problem but instead collapsed, making no discernible progress. I was in Copenhagen as a volunteer campaigner lobbying various delegations, and I’d spent most of the two weeks wandering about the vast conference centre with a button in my lapel that read “1.5 to Stay Alive”, part of a campaign mounted by the low-lying nations whose very existence was at risk. Dr Albert Binger, director of the Centre for Environment and Development at the University of the West Indies, emerged as a spokesman for the Association of Small Island States: “Our ports, airports, roads and settlements will no longer be able to survive two degrees,” he said. “Some countries will flat out disappear. You have a problem in the Pacific [with] Kiribati, Tuvalu, islands in Papua New Guinea and Fiji, across Asia [to] the Maldives.”

Australians may be forgiven for having a similar opinion – after all, the slightly-less-than-one degree by which we’ve already raised the global average temperature allowed your recent “angry summer” of flood and fire. Averages hide extremes: all over the world we’re seeing government weather services adding new colours to their charts to describe new conditions. Rather than citing all the records that have fallen across your continent in recent times, it’s probably enough to point out that when you have hundred-year floods every few months, something is seriously out of balance, and that when droughts are crashing koala populations, it’s a signal that something very new is afoot.

It’s not just Australia. Record rainfalls inundate some spot on the globe almost every week (because warm air holds more water vapour than cold, loading the dice for greater downpours), while vegetation in the Arctic has already crept north as much as seven degrees of latitude. As alluded to earlier, new Cryosat data indicates there’s only 20% as much ice in the summer Arctic as there was 40 years ago. It’s worth thinking about: that white sheet once reflected sunlight back out to space, but the blue water there now absorbs it instead, amplifying the reaction. We’ve taken one of the Earth’s biggest physical features and broken it. If that’s what one degree of warming will do, it’s daring to the point of stupidity to find out what two degrees will bring.

Environmentalists and scientists lost that fight. In the end, political realism bested scientific realism, and the world settled on the two-degree target – it’s essentially the only thing about climate change the world has settled on. By 31 January 2010, which was the deadline for signing on to the Copenhagen Accord, 141 countries, representing 87.24% of the world’s carbon emissions, had endorsed the two-degree target, and many more have been added since. Only a few countries, such as Sudan, Bolivia, Cuba, Nicaragua and Venezuela, have rejected it – the signatories include not just the US and China, but also rising powers like India, Brazil, Russia and Indonesia. Not to mention Australia. The official position of planet Earth is that we should not raise the temperature by more than two degrees Celsius.

The next stage of our maths lesson requires finding out how much more carbon we can emit into the atmosphere and still stay below two degrees. Here the answer is easier: a wide variety of computer models have converged on the figure of about 500 additional gigatons of CO₂. The number comes with no guarantee that it will keep us below two degrees of warming, just with an 80% chance. Worse odds than Russian roulette, but it’s only our planet.

Still, 500 gigatons is a lot. A gigaton is a billion tons, and a billion tons is incomprehensible. Except we’re producing more than 30 billion tons a year as a planet already, and that number has been growing by about 3% a year. Which gives us about 15 years before we go soaring past the 500-gigaton threshold. To avoid doing that, the computer modelling shows that the world’s carbon emissions would have to peak in 2015 and then come hurtling down. That’s why Australia has enacted its controversial carbon-pricing scheme, in an effort to do its share in keeping the world below that threshold. Australians, like Americans, will still consume vastly more energy per capita than most, but it’s a gesture in the right direction, in helping the world in its great task to get the arithmetic to line up.

Now let’s complicate matters. Let’s factor in these new coalmines, the ones that the various Labor ministers found it so irresponsible and depraved for anyone to organise against. (I’m assuming the Liberal leaders found the plans so horrifying they said nothing that could be printed in a family newspaper.) In fact, let’s just take one set of mines, in Queensland’s Galilee Basin. Those mines contain enough carbon that, were the recoverable coal to be mined and burnt, it would fill up 6% of the remaining buffer between us and two degrees. That valley alone contains about as much carbon as the oil and gas reserves owned by ExxonMobil, the world’s richest company. There are plenty of other coalmines planned for Australia (not to mention, say, the recent shale oil find in South Australia’s Arckaringa Basin, which, according to its promoters, contains as much as 233 billion barrels of recoverable shale oil, more than the estimated oil in Canada, Iran, Iraq or Venezuela, and essentially equivalent to what’s left in Saudi Arabia). At present, Australian coal burnt overseas already produces considerably more carbon emissions than every-thing Australians do at home. A recent report from the Climate Institute shows that if Australia builds up its coal exports as currently planned, it would produce 30% of the carbon needed to push global warming beyond two degrees. By 2020 the country’s coal burnt abroad will be producing three times as much CO₂ as all the country’s cars and factories and homes; by 2025, four times. And so on.

In other words, if you were serious about slowing down global warming, you might argue it misses the point to focus mostly on the behaviour of ordinary Australians, and not on the behaviour of Australian mine owners. I don’t wish to be misunderstood: it’s very important that Australia has put a price on carbon, and very important that this measure not be overturned as a result of the next election. It’s a modest start that has had good effects in opening up the debate around the world, and has apparently reduced domestic energy use. It has also spurred development of renewable energy across the continent: by early 2013 the business press was reporting that wind power was now cheaper than coal power in Australia. Credit to Prime Minister Gillard, and credit to the Greens who helped to force her hand. But far more credit to those dastardly schemers trying to “get in front of critical projects and try to slow them down in the approval process”. Getting Australians to rein in their carbon burning counts for something, but it’s at least as important – and in mathematical terms far more important – to rein in the huge expansion of Australia’s coalmines.

If you were serious about global warming, you might argue it misses the point to focus on the behaviour of ordinary Australians, and not on the behaviour of Australian mine owners.

That is to say, individual changes alone won’t make the maths work. It demands structural shifts on a massive scale.

The global coal, oil and gas industry, even before it opens new mines and drills new wells, already has more than five times as much carbon in its reserves as we can burn: equivalent to 2795 gigatons of CO₂ against the 500 gigatons even the most conservative governments would allow. We’re already deep in a hole, and the first rule of holes is that when you’re in one, you stop digging.

So let’s consider the arguments, not fully stated but easy enough to parse, that must have undergirded the outrage at the Greenpeace report.

The first would be: “This carbon shouldn’t be held against us. We’re not using it, just selling it.” This is true. Much of the coal is already being burnt in China, and a lot of the new supply, to judge by the companies supplying the financing, is heading for India. But of course the atmosphere doesn’t care where carbon comes from – it mixes freely around the planet in a matter of days. That’s why they call it global warming.

You could, of course, argue that the coal is doing great things in Asia. There’s some truth to it: cheap energy has been one of the factors pulling people out of poverty at a rapid rate. But by now it’s obvious to anyone looking at the air over Beijing that it’s at best a mixed blessing, even before you figure in the climate effects. A study released in March estimated that the smoke pouring from India’s power plants was killing up to 120,000 people annually. Once you include the climate, the damage really mounts. We know that the effects of climate change are likely to hit poor countries the hardest. A World Bank report late last year made it very clear that there was no chance of “development” in a world with fast-rising temperatures. Whereas Craig Emerson might fear “mass starvation” if people “lodged legal challenges” to Australian coalmine expansion, the current thinking of agronomists, expressed in a study by Stanford and University of Washington researchers, is that each degree rise in average global temperature from now on will cut grain yields by 10%. This is an easy enough scenario to contemplate in the US after last summer’s devastating drought. Even the most basic underpinnings of our civilisation, especially in its poorest reaches, are called into question: research released earlier this year by the US National Oceanic and Atmospheric Administration (NOAA) suggested that increased heat and humidity had already cut the ability of human beings to work outside by 10%, a figure that is expected to double by mid century.

If you sell something with knowledge of the damage its consumption will do, you bear some responsibility for that damage.

An analogy with a drug dealer doesn’t strike me as perfect in this case, though, because the whole planet shares, as it were, a vein. India burns the coal, but Australia burns up too.

A second argument of the outraged ministers might be that it won’t do any good if Australia halts its coalmine expansion, because someone else will just take up the slack. Again, there’s a kind of truth here. Greenpeace, for instance, recently published a list of 14 enormous mining projects around the world that would take us past a “point of no return” climatically. Really, almost any one of them is big enough to overload the remaining space for carbon in the atmosphere. Take the tar sands of Canada, a mucky oil deposit in northern Alberta. The oil contained in those sands, and another similar deposit in Venezuela, has more carbon than all the oil we’ve burnt so far in the world, according to James Hansen. That’s why, he explained in 2011, it would be “game over for the climate” if we burnt it on top of all else that we were burning. And that’s why he’s been willing to go to jail twice to try to stop the biggest pipeline aimed at draining those tar sands, the so-called Keystone XL pipe to the Gulf of Mexico. I’ve been to jail twice myself in helping to organise the largest civil disobedience campaign about any issue in the US in 30 years. It’s not completely ludicrous to imagine keeping those tar sands underground – a vast coalition of environmentalists, native Americans, ranchers and farmers is trying to do just that.

Here’s another way of looking at it. Twenty years ago or so, the world’s scientists figured out it was a very bad idea to cut down the Amazon rainforest. A lot of people thought it was hopeless to try to slow the deforestation, but the Brazilian public and their government have actually done a pretty credible job. And this is a poor country with relatively limited options. Consider, by contrast, Australia – highly educated, full of entrepreneurs, plenty of capital. There’s nothing you can figure out how to do except dig up black rocks and send them to China to burn? The only possible way to even hope to persuade the Indonesians and the Kazakhs not to pursue their own mega-projects is to show some restraint in the rich parts of the world, unleash entrepreneurs on a drive for renewables instead, and use the shift as a tool of aggressive diplomacy.

The need to keep all this oil in the soil, all this coal in the hole, is precisely why we need to envision the planet as a planet, not just a collection of nations, each pursuing its own advantage. We’re at a moment when the alternatives seem realistic. Wind power, as I said, is now as affordable as coal in Australia, not to mention the power from the sun that shines on your continent, the geo-thermal power bubbling beneath it and the tidal power at its fringes. Look at Germany, stuck at higher latitudes – yet there were days in the last northern summer when it generated more than half the power it used from solar panels within its borders.

Every ounce of dirty, cheap coal shipped out of Australia prolongs the period when human beings pour carbon into the atmosphere. It undercuts the shift to renewable energy as surely as selling big bags of discount potato chips undercuts the will to diet. There’s no mystery here at all, and that’s why I think the reaction of Australian leaders to the news that someone might oppose the country’s coal expansion owed very little to logic. I’m guessing that it owed a great deal instead to fear: specifically to the fear of what the very rich people who own coalmines can do to a political career.

I don’t know your carbon barons, but ours in the US are pretty awful. The Koch brothers, for instance, are the third and fourth wealthiest people in the country, and much of their fortune comes from the tar sands. They’ve spent incredible sums bankrolling conservative causes and outspoken climate deniers in the US, thus making sure that fossil fuel companies are allowed to pour their waste into the atmosphere for free (a privilege granted to no other business). My sense is that yours may be pretty awful, too. One of the stories I found, as I tried to unravel the mystery of why politicians were so upset at any challenge to coal exports, concerned a mining magnate named Clive Palmer, who explained that the whole plan was actually a CIA plot.

Official Australia seems to be stuck in a bizarre state of denial, the kind where you acknowledge that you have a problem, but not that you need to do anything about it.

As it turns out, Australia is not just a bunch of coal barons. That Greenpeace report was not the first time anyone had raised the issue of Australia’s coalmines, even if the reaction of Labor politicians made it sound that way. The lucky country has also yielded alternative energy entrepreneurs and engineers, like Martin Green and Shi Zhengrong. Your Investor Group on Climate Change is one of the world’s biggest and most engaged. Your activists include some of the best – the Australian Youth Climate Coalition, as well as people like Simon Sheikh, Tim Flannery, Clive Hamilton and even Malcolm Turnbull. I had a great dinner once with the bald guy from Midnight Oil, and a couple of nights later Peter Singer, the ethicist and animal liberationist, took me to the best vegan restaurant in Melbourne, which was sort of like taking communion with the pope. I even Googled enough to figure out that some folks defended the Greenpeace plan despite the government’s tantrum. The former head of Rothschild Australia, Peter Martin, for instance, said, “The hysterical comments by politicians and companies are clearly self-serving. [Greenpeace and friends] are just trying to protect the interests of future Australians from exploitation.” Which seems about right.

Official Australia seems to be stuck in a bizarre state of denial, the kind where you acknowledge that you have a problem, but not that you need to do anything about it. After the recent farcical Labor leadership spill, I read in the newspapers about the new resources minister, a fellow with the apropos name of Gary Gray. He used to be a climate sceptic, calling global warming “pop science”, but now believes that there is “no doubt” about the link between carbon emissions and global warming. He claims “we can address” the problem but not, apparently, by changing anything we’re doing now. He wouldn’t, he said, be any different from his predecessor, or indeed his successor should the Liberals prevail in the next election. “I fit very comfortably in that vein,” he said. Yes, that will be the same vein mentioned earlier: the one the planet shares.

I understand why no one in power actually wants to take on these questions. It is absolutely true that getting off coal and gas and oil will be hard, perhaps the hardest transition civilisation has ever forced itself through. It’s true that for Australia it will mean rethinking what the economy looks like – for instance, by finding new jobs for people now working in the mines: putting up and maintaining solar panels, perhaps, or building windmills, which involves transferable skills from boilermaking to welding. It will mean changes in the way all of us behave from day to day. It will require true global diplomacy, since no country can conquer climate change on its own.

But it will require, first and foremost, telling the truth about where we stand. The truth is that Australia’s coal has to stay in the ground, along with Canada’s oil, and the huge reserves of gas in the US, and so on. If that carbon is poured into the atmosphere, the equation laid out above won’t work, and the planet will overheat disastrously. It’s climate change, not protest, that will cause “mass starvation”, raise “real concerns for safety” and count as “economic vandalism”. You could almost say it’s “completely irrational and destructive”. And yet it’s under way.